In a decision that strengthens Alexandria's recent get-tough stance with developers, a Virginia Circuit Court judge ruled yesterday that the city acted legally when it blocked plans to build an 11-story office building on W. Duke Street.

Judge Donald H. Kent's opinion, allowing the city to invoke an ordinance passed after plans for the building site were filed with the city, effectively barred First Ameriland Development and Construction Co. from constructing a high-rise medical office tower at Duke Street and Quaker Lane.

"It's a very important victory," said Alexandria City Manager Vola Lawson. "It says that you have to have specific site approval before you have a vested right to develop a property . . . and only the City Council can give you that."

The opinion may support the city's position in dealing with other developers seeking to exempt themselves from changes in local ordinances. The City Council, which faces a major court challenge from a developer on a similar issue, has taken a harder line on growth and traffic issues in recent months.

First Ameriland told city officials last October that it wanted to build a 150-foot-high building at the busy Duke Street intersection. But in November the City Council imposed a 50-foot height limit on buildings along W. Duke Street.

The developer filed suit against the city in February, contending that the height limit should not apply to its building and that the city had not given adequate public notice before passing the ordinance. Kent's opinion rejected both claims.

In the past, developers have contended that they can exempt themselves from changes in local ordinances simply by filing early site plans with city planning officials. Kent's opinion, however, says that such filings are not enough. A developer, Kent said, must have evidence of "governmental approval of the proposed land use" to be exempted from a new ordinance.

"Absent governmental approval of the proposed land use," Kent wrote, "the plaintiff does not have a vested right to the approval of the site plan application."

Potomac Greens Associates, a developer whose plans for a massive $500 million office complex along the George Washington Parkway south of National Airport have been rejected by the City Council, has filed a lawsuit contesting a point similar to that raised by First Ameriland.

Potomac Greens contends that it should be exempted from an ordinance requiring developers to take potentially expensive steps to reduce traffic congestion because it had filed a site plan before the ordinance was passed.

Yesterday's decision "reinforces the city's position with regard to Potomac Greens," Lawson said.

John Fagelson, an attorney for First Ameriland, said his client probably will appeal Kent's ruling to the Virginia Supreme Court. "This was the judge's decision, but it wasn't the final one by any means," Fagelson said. "This case was probably going to Richmond no matter who won."

Mike Hicks, president of the Alexandria Federation of Civic Associations, praised Kent's decision, saying it would enable the city to deal more effectively with growth-related problems. The federation has frequently urged the City Council to adopt slow-growth positions.

"This puts us in ecstasy," Hicks said. "It gives the city some tools to help bring about orderly development. Compared to the past, the city is now putting itself in the role of a mediator on growth questions."